1. Technical Field
The present invention relates to a transfer printing field, and more particularly, to a transfer printing substrate capable of implementing high alignment and transfer rate even in a case of an ultra-thin film element by using a pillar structure, a manufacturing method thereof, and a method of transfer printing.
2. Description of the Related Art
Future electric and electronic elements need to have shape variability. For example, the reason is that the elements may be required to repeatedly deform shapes thereof such as clothes or human body organs, or may be attached to a building outer wall having various forms of surfaces in a deformed shape to thereby be maintained. Mechanical flexibility and elasticity enough to deform the form may be implemented by realizing an ultra-thinness of a structure of the element or reducing a thickness of a substrate itself. However, in the case in which the thickness of the substrate is reduced to several tens micrometers, the substrate is likely to be twisted or bent during a manufacturing process. Therefore, in order to secure stability required for an element process, a handling substrate supporting an ultra-thin film substrate has been used. In order to attach the ultra-thin film substrate supported by the handling substrate as described above to a desired surface, a transferring method having high alignment and transfer yield is required. For example, in order to adjust bonding force between the ultra-thin film substrate and the handling substrate, a scheme interposing a sacrificial layer between the substrates and removing the sacrificial layer after completing the process has been used. After the bonding force between the substrates becomes weaken by removing the sacrificial layer, the substrates are transferred onto the desired surface.
However, in the case in which the sacrificial layer is removed by an etching solution, the ultra-thin film substrate on the handling substrate floats and deviates from an original position, thereby decreasing alignment, or the ultra-thin film substrate immersed during an etching process is strongly bonded to the handling substrate, thereby decreasing the transfer yield.
As methods for solving the above-mentioned problems, a method of introducing a support maintaining a mechanical bond by forming a concave structure in the handling substrate or increasing alignment of the element by residue confined in a structural form during the etching process using a polymer sacrificial layer has been researched, and in addition to this, methods using a laser or using heat in order to decrease the bonding force between interfaces have been developed. There are problems in that the etching solution vulnerable to damage is used, a floating phenomenon of the pattern is caused due to a long etching time, it is costly, it is likely to be damaged by heat, and so forth.
Therefore, in manufacturing the ultra-thin film element having high flexibility and elasticity, a method capable of securing stability of a process and realizing high alignment and transfer yield is demanded.